Method of and apparatus for heat insulation.



R. A. FESSENDEN.

METHOD OF AND APPARATUS FOR HEAT INSULATION.

APPLICATION FILED MAR. 6. I916.

Lg m fio Patented Ap1z22,1919.

WWII!) A. FESSENDEN, 0F BEBOKLINE, MASSACHUSETTS.

a 'TUS FOE, EAT INSULATION.

Specification of Letters Patent. Patented Apr. 22, 11.919.

Application filed March 3, 1916. Serial No. 82,417.

To all whom it may concern:

Be it known that T, REGINALD A. FESSEN- DEN, a citizen of the UnitedStates, residing at Brookline, in the county of Norfolk and State ofMassachusetts, have invented certain new and useful Improvements inMethods of and Apparatus for Heat Insulation, of which the following isa specification.

My invention relates to methods and apparatus for preventing the flow ofheat; especially from spaces where the temperature is high; and moreespecially still, from the cylinders of heat engines; particularlyengines of the type shown in U. S. Patent 1,132,465.

My invention consists in the use of certain types of alloys which I havediscovered possess properties which make them particularly etlicient forpurposes of heat insulation; and also enerally in increasing theelliciency of heatmg chambers and ther mal engines. The drawing formin'a part of this specification shows, partly d iagrammatically and partlyin section, an application of the method and apparatus to a heat engine,of the type shown in U. S. Patent 1,132,465.

Here 11 is the cylinder and 17, 17 the p1stons. These are covered by theheat insulating liners 13, 14, 14, formed of the alloys described laterin this specification. Between the liners and the cylinder and pistonbodies are also heat insulating laminae 12, 15, of air or magnesia, orchrome oxid, or tungsten oxid, of cement or lime or thin strips of alloyor layers of mica covered with alloy strip, or other suitable material,for example enamel or porcelain, or steel wool, or slag wool, or alloywool.

The scavenging receiver 20 delivers am into the cylinder 11 through theports 18, 18.

The burnt gases escape through the exhaust,

ports 19, 19. The piston rods, 21, 21 drive the cranks 22, 22 and thecrank-shafts 23, 23 are synchronized by the chain belt 25 and pulleys24, 24'.

Oil from the pipe 27 is injected into the cylinder through the injectionvalve 26, by

means of air, or Iburnt gaseous products of. combustion, or steam,preferably generated by the heat of the exhaust gases of the engine, andsuper-heated from the pipe 28, and the'valve 26 is operatedelectromagnetically by means of the commutator conslsting of theinsulating part 32, and the conducting segment 33, mounted on the shaft23. 30 and 31 are brushes, 29 is a battery, and when the circuit iscompleted by the conducting segment 33 passing under the brushes 30, 31,the battery 29 actuates the magnet of the electromagnetic injectionvalve 26, lifting the valve seat, and the oil 1s injected. The time ofinjection may be varied by shifting the brushes 30, 31, and the lift ofthe valve 26 by varying the strength of the current flowing from thebattery 29.

The liners of a thermal motor should have the following properties, a onothers 1. They should not be easily %usible.

2. They should not be oxidizable or acted on by the products ofcombustion.

3. They should not take up heat readily from the hot gases resultingfrom the ignition of the combustible.

There are numbers of metalswhich fulfil the first two conditions, forexam le, gold, silver and platinum. Tun ten ihlfils the first, but notthe second. ut applicant has never been able to find any descrip tion ofany materials suitable for the purpose which fulfil all three.

Applicant has however discovered that certain well known and otherunknown, alloys fulfil all three, and has tested same experimentally.Broadly speaking these alloys consist of a metal of high melting pointcombined with a metal whose oxid or carbid insulates heat well at hightemperatures. So much appears from the applicants experiments. And thetheory which applicant has formed as the result of his experiments isthat the alloy is acted on by the hot gases at its surface and that thehigh melting point metal is oxidized and carried away, and the metalwith the heat insulating oxid is oxidized and the oxid remains on thesurface, sometimes in so thin a film as to be transparent or yellowishor brownish, or bluish, and resists the further transfer of heat fromthe burning combustible to the liner. This theory may not be correct,but it appears to account for the facts, so far observed.

Suitable alloy forming high melting point metals are those of the irongroup, though others may be used. Suitable metals of the thermallyresisting oxid .class are chromium, magnesium, aluminium and tungsten,though others may also be used.

The alloys are not limited to two elements, as several may be used.

A suitable way to test the alloys is to take a six inch square plate,stand it on edge and apply a high temperature blow pipe to its centerand see how long it takes to get red hot on the opposite side. Manymetals and alloys will resist even the acetylene-oxygen blow pipe,especially if water cooled at the back, for example platinum andplatinum-irridium and some of the alloys used for making safes. But thealloys forming the liners used by applicant have the additionalproperty, discovered by applicant, that they not only resist'the actionof the blow ipe, but also, in addition, do not take up eat readily fromthe hot gases of the blow pipe, as is shown by their taking a longertime by far to become red hot. on the opposite side to the blow-pipe.

Some of the alloys which have shown this new property are well known,others not.

A very suitable alloy is one consisting of iron,

nickel, or cobalt, with about 10% of chro mium, and the addition of afew .per cent. of tungsten seems to still further improve the heatinsulating properties of the alloy. Possibly because the double oxid ofchromium and tungsten is a better heat insulator at high temperaturesthan the alloy of chromium or chromium and iron or nickel is. Whateverthe reason I have found this 7 alloy particularly suitable, though theadmixture of small amounts of other materials such as manganese etc.does not seem to render it less heat insulating, i. e. it is not Wherethe heating is many times repeated and mechanical strength is necessary,it is better to have a pure material alloy, for example nickel alone andabout 10% to 15% chromium, or cobalt alone and chromium. Up to 40%chromium or may be used, but the effect does'notincrease so rapidlyabove 10%.

Instead of operating the valve 26 by a battery, it may be actuated bythe discharge of condensers, first charged and then discharged throughthe circuit, the number of condensers used depending on the time thevalve is required to be open. The cylinder liners may be conical,instead of cylindrical, as also the cylinders.

The alloy wool is made by blowing the -alloys, such as chrome-nickel,chrome-iron,

chrome-cobalt, or magnesium bronze, into fine filaments, like slag woolor steel wool. Not only does the thin film of alloy oxid insulate theheat, but, being almost transparent in thin layers, it reflects the heatalso. Consequently the heat from the hot ases is not readily convectedor absorbed 1nto. the alloy liner of the engine or gun or other thermalmotor. What I claim is 1. The combination of a high temperature chamberand a thermo insulator for said chamber, consisting of'a coating formedby heating an alloy of a high temperature point metal and a metal whoseoxid is a good thermal insulator at high temperatures.

2. A heat insulating liner for thermal motors consisting of a coatingformed by heating an alloy of a metal of the iron group and chromium,

REGINALD A. FESSENDEN.

